This invention relates to optical communication systems and more particularly to a fiber optic cable and transceiver connector system, a support system for the optical components of the transceiver, and fiber optic cable connectors.
Optical couplers are now used to communicate optical signals over short and long distances between, for example, two computers, two circuit boards in one computer, and even two different chips on the same circuit board.
The technology associated with electronics has evolved extremely rapidly over the last 40 years. Computers and related peripheral equipment, satellite, and communication systems are becoming ever more sophisticated and powerful. A key factor leading to every increasing demand for faster data transfer rates is the need to perform tasks that are highly complex. Such tasks include digital signal processing, image analysis, and communications.
Data transfer, however, remains a gating capability. This issue holds true for data transfer within an integrated circuit, from one chip to another, from hybrid circuit to hybrid circuit, from one integrated circuit board to another integrated circuit board, and from system to system.
Increasing the data transfer rate can be done in any of several ways. Originally, the scheme used was to increase the number of data transfer lines, i.e., transfer the data in parallel. The historical progression according to this scheme has been in powers of two: The first real integrated circuits had 4 bit buses; next came 8 bit buses, which were then superceded by 16 bit buses; currently, 32 bit buses are the standard; and 64 bit buses are in development.
Such increases have typically come in two phases. In the first phase, a factor of two increases in the number of bits being processed takes place within the chip. Then, as the technology matures, the number of bits on the bus off the chip increases. Under such an approach, there is always a greater processing capability available on a chip than off it, and so, unfortunately, advances in chip design must wait for the rest of the system to catch up.
Accelerated development of wider bit buses (e.g. 128, 256, etc.) has been impeded by several factors including the practical limitation on the size of the mechanical connectors, the noise inherent in the signals arriving nearly simultaneously, the reliability of wide pin connectors, and the power required to drive multiple lines off-chip. As a result, many of today""s successful networks are serial or relatively narrow (e.g., Gigabyte Ethernet or Myrinet) and transmitted over a single co-axial cable or possibly a single pair of optical fibers.
Another approach is to simply increase the speed with which the information is processed. Early microprocessors functioned at 4 MHz, and, with each succeeding year, the raw speed of microprocessors increases. Currently, processor speeds in excess of 400 MHz are common and processors with speeds in excess of 1 GHz are in the offing.
Increasing the processor speed is not without challenges, however, because increasing the speed also increases power requirements, introduces skew problems across the channel, and usually requires more exotic processing than is standard practice. Combining the two approaches, i.e., making wide and fast networks, is difficult because the combination of the problems inherent in each approach is overwhelming for existing technologies.
In response, integrated circuit technology that enables bi-directional, high-speed optical rather than electrical interconnections has been developed. This technology allows laser emitters and detectors to be integrated onto a semiconductor substrate, making electrical connection with electronic circuitry previously built on that substrate.
Thus, optical rather than electrical communications between electronic devices is accomplished. An optical transmitter-receiver module typically includes both light emitting devices such as vertical cavity surface emitting lasers (VCSELs) and light detecting devices such as photodiodes. Such a module may include separate chips, or more typically, the VCSELs and the photodiodes are grown on the same substrate. See U.S. Pat. No. 5,978,401 incorporated herein by this reference.
Driver-receiver circuitry modules, typically in the form of ASIC chips, include driver circuitry which receives electrical signals from one electronic device and which, in response, drives the VCSELs accordingly. The ASIC also include receiver circuitry for receiving signals from the photodiodes and, in response, which processes those electrical signals providing an appropriate output to the associated electronic device.
The combination of the VCSELs and the photodiodes and the ASIC circuitry is typically called an optical transceiver. One way to hybridize the VCSELs and the photodiodes and the ASIC receiver circuitry is by flip-chip bonding. See U.S. Pat. No. 5,858,814, incorporated herein by this reference.
A fiber optic cable then has one end connected to one transceiver and the other end connected to another transceiver via optical connectors.
As the density of the arrays of emitters and detectors increases, coupling a fiber optic cable to these arrays becomes an increasingly arduous task. Design considerations include properly aligning the active area of each emitter and detector with a particular fiber of the fiber optic bundle, fashioning reliable removable connectors which maintain alignment over repeated coupling and decoupling of the optical fiber bundle to the arrays, accommodating for the circuitry and wiring electrically connecting the arrays to other circuitry, keeping the arrays clean, manufacturing studies to insure that the cost of such couplers is not prohibitive and that they are not unduly complex, and insuring that when the coupler is removed from its transceiver, laser light emitted by the arrays of the transceiver does not harm the eyes of personnel in close proximity to the transceiver.
It is therefore an object of this invention to provide an improved fiber optic cable and transceiver connection system.
It is a further object of this invention to provide such a system which simplifies the coupling of a fiber optic cable to high density arrays of emitters and detectors.
It is a further object of this invention to provide such a system which makes it easier to properly align the active area of each emitter and detector with a particular optical fiber of the fiber optic bundle.
It is a further object of this invention to provide such a system which is highly reliable and which maintains alignment over repeated coupling and decoupling of the optical fiber bundle to the transceiver.
It is a further object of this invention to provide such a system which includes a standoff between the cable and the transceivers to accommodate the circuitry and wiring associated with the active arrays.
It is a further object of this invention to provide such a system which prevents contamination of the transceivers.
It is a further object of this invention to provide such a system which is not cost prohibitive and which is not unduly complex.
It is a further object of this invention to provide such a system which insures that when the fiber optic coupler is removed from the transceiver laser light emitted by the arrays of the transceiver cannot does not harm the eyes of the personnel in the area.
The invention results from the realization that if a support structure is fabricated about the emitter and/or detector arrays at the time the arrays are flip-chipped bonded to their associated circuitry modules, any associated optical components can be supported on the support structure on or over the arrays thus protecting the arrays and making it easier to provide a fiber optic bundle coupler which reliably aligns the fibers of the bundle with the individual emitters and/or detectors of the arrays.
This invention results from the further realization that if a face plate is used as an optical component to over-sample light from the arrays, then the face plate will also provide the required spacing between the fiber bundle and the arrays necessary to accommodate the circuitry surrounding the arrays and also that fiber alignment can now be more easily effected if a fiber bundle alignment plate is used in conjunction with the face plate and individual fibers of the bundle are threaded through the orifices of the alignment plate.
This invention results from the further realization that the difficulty and cost of manufacturing molded coupler components to the exact tolerances required to effect the necessary alignment required in a system with arrays of many emitters and detectors can be overcome by forming insert plates by precise etching processes and placing the insert plates in the individual molded coupler components to thus more reliably insure that the optical fibers are aligned with the arrays.
This invention results from the further realization that if the female half of the optical coupler is fashioned with a spring biased trap door, then, when the male half of the coupler is removed form the female half, any laser light emitted by the arrays will be shielded by the trap door thus preventing harm to the eyes of personnel in the vicinity of the transceiver.
This invention features a fiber optic cable and transceiver connection system comprising at least one array of emitters or detectors on a circuitry module; a support structure about the array; a collimator on the support structure; a fiber bundle alignment plate positioned over the collimator including at least one array of orifices therethrough; an alignment coupler including an opening therein for receiving the collimator; and means for fixing the fiber bundle alignment plate in a precise orientation with respect to the alignment coupler to establish a precise registration between the individual emitter or detectors of the array and optical fibers located in the orifices of the alignment plate.
The means for fixing may include a pair of pins extending from the alignment plate and corresponding orifices in the alignment coupler which receive the pins. The circuitry module is typically an ASIC which includes an array of emitters in the form VCSELs and an array of detectors in the form of photodetectors.
The circuitry module may be mounted on a substrate such as a heat sink. A set of standoffs are positioned upstanding from the substrate and the alignment coupler is mounted on the standoffs. Fasteners secure the alignment coupler with respect to the substrate.
The system may further include a fiber ferrule housing the alignment plate, a pin holder coupled to the fiber ferrule, a connector plug body housing the fiber ferrule, and means for releasably attaching the connector plug body to the alignment coupler. In the preferred embodiment, the collimator is a faceplate.
A fiber optic connector in accordance with this invention includes an alignment coupler including a housing thereon; a fiber bundle alignment plate mounted to a ferrule receivable within the housing of the alignment coupler; means for aligning the alignment plate with respect to the alignment coupler; and means for releasably locking the ferrule in the housing of the alignment coupler.
The means for aligning may include a pair of pins extending from the alignment plate and a pair of corresponding orifices in the alignment coupler. The means for releasably locking the ferrule in the housing of the alignment coupler typically includes: a plug body housing the ferrule, the plug body including a pair of outwardly extending ridges; and a coupler body with a channel for receiving the coupler housing and the plug body, the channel of the coupler body including a pair of latching members biased over the outwardly extending ridges of the plug body, the plug body further including a sliding mechanism for urging the latching members away from the outwardly extending ridges to remove the plug body from the coupler body.
A fiber optic connector in accordance with one embodiment of the subject invention includes a female portion and a male portion. The female portion includes an alignment coupler including a housing thereon, and a coupler body with a channel which receives the coupler housing. The male portion includes a fiber ferrule including an alignment plate, and a plug body housing the fiber ferrule. Such a connector further includes means for accurately positioning the alignment plate in the housing of the alignment coupler, and means for releasably coupling the male portion to the female portion.
The means for accurately positioning the alignment plate in the housing of the alignment coupler typically includes at least one pin extending from the alignment plate and at least one orifice in the alignment coupler for receiving said pin. The means for releasably coupling the male portion to the ferrule portion may include a coupler body place over the alignment coupler, the coupler body including at least one latch member, and at least one ridge on the plug body. The latch member is positioned over the ridge on the plug body when the male portion of the connector is coupled to the ferrule portion of the connector.
This invention also features a support system for a fiber optic transceiver, the support system comprising: a circuitry module; at least one array of active elements on the circuitry module, the individual active elements separated by a gap; and a structure supporting optical components on or above the individual active elements. The supporting structure may surround the array of active elements. Alternatively, the support structure includes a first set of spaced members in the gaps between individual active elements running in a first direction and a second set of spaced members in the gaps between individual active elements running in a second direction orthogonal to the first direction. In still another embodiment, the support structure includes discrete posts in the gaps.
The method of forming a support structure for a fiber optic transceiver in accordance with this invention includes forming an array of individual active elements in a wafer by etching channels between the individual active elements, said channels formed in the wafer deeper than required to achieve electrical isolation between individual active elements; inserting a flowable substance into the channels and allowing the substance to harden; flip chip bonding the wafer to a circuitry module; and removing all wafer structure other than the individual active elements and the hardened substance.
This invention also features a fiber optic connector comprising: a molded alignment coupler including a base plate, an opening in the base plate, and at least one alignment channel in the base plate, a housing upstanding from base plate surrounding the opening and the at least one alignment channel; and an insert plate in the housing, the insert plate including an opening etched therethrough corresponding to the opening in the base plate of the coupler, and at least one channel etched in the insert plate corresponding to the alignment channel of the coupler.
The channel of the insert plate is preferably conical in shape and the insert plate may further includes at least one keyway and the base plate then includes at least one key for positioning the insert plate on the base plate.
The connector may further include a fiber bundle alignment plate mounted to a ferrule receivable within the housing of the alignment coupler; means for aligning the alignment plate with respect to the alignment coupler; and means for releasably locking the ferrule in the housing of the alignment coupler.
The means for aligning may include at least one pin extending from the alignment plate receivable in the alignment channel of the alignment coupler. The means for releasably locking the ferrule in the housing of the alignment coupler may include a plug body housing the ferrule, the plug body including a pair of outwardly extending ridges; and a coupler body with a channel for receiving the coupler housing and the plug body, the channel of the coupler body including a pair of latching members biased over the outwardly extending ridges of the plug body, the plug body further including a sliding mechanism for urging the latching members away from the outwardly extending ridges to remove the plug body from the coupler body.
The connector may have a female portion including a coupler body with a channel which receives the coupler housing; and a male portion including: a fiber ferrule including an alignment plate, and a plug body housing the fiber ferrule; the connector further including means for accurately positioning the alignment plate in the housing of the alignment coupler; and means for releasably coupling the male portion to the female portion.
The means for accurately positioning the alignment plate in the housing of the alignment coupler may include at least one pin extending from the alignment plate, the pin received in the alignment channel of the alignment coupler. The means for releasably coupling the male portion to the female portion typically includes a coupler body placed over the alignment coupler, the coupler body including at one latch member, and at least one ridge on the plug body. The latch member is positioned over the ridge on the plug body when the male portion of the connector is coupled to the ferrule portion of the connector.
This invention also features a fiber optic cable connector comprising: a coupler body with a channel for receiving a connector plug therein; and a door spanning the channel, the door biased to cover the channel but displaceable with respect to the channel when the plug body is received in the channel to prevent light from escaping the channel when the plug body is removed from the channel. The door is usually hinged on each end to the channel and includes at least one spring biasing the door in a position spanning the channel.
A fiber optic cable and transceiver connection system in accordance with this invention may include at least one array of emitters on a circuitry module; a support structure about the array; a collimator on the support structure; a fiber bundle alignment plate positioned over the collimator including at least one array of orifices therethrough; a coupler including an opening therein for receiving the collimator; and means for preventing light from the emitters from escaping the coupler.
The system may further include a pair of pins extending from the alignment plate and corresponding orifices in the coupler which receive the pins. The circuitry module may be an ASIC which includes an array of emitters in the form VCSELs and an array of detectors in the form of photodetectors. The circuitry module may be mounted on a substrate and the system then further includes a set of standoffs upstanding from the substrate and the coupler is mounted on the standoffs. Fasteners secure the coupler with respect to the substrate.
The system may further include a fiber ferrule housing the alignment plate, a pin holder coupled to the fiber ferrule, a connector plug body housing the fiber ferrule, and means for releasably attaching the connector plug body to the coupler.
The collimator is typically a face plate and the means for preventing may include a coupler body with a channel for receiving a plug therein; and a door spanning the channel, the door biased to cover the channel but displaceable with respect to the channel when the plug body is received in the channel to prevent light from escaping the channel when the plug body is removed from the channel. The door may be hinged on each end to the channel and typically includes at least one spring biasing the door in a position spanning the channel.
A fiber optic connector according to this invention has an alignment coupler including a housing thereon; a fiber bundle alignment plate mounted to a ferrule receivable within the housing of the alignment coupler; means for aligning the alignment plate with respect to the alignment coupler; means for releasably locking the ferrule in the housing of the alignment coupler; and means for sealing the alignment coupler.
The means for aligning typically includes a pair of pins extending from the alignment plate and a pair of corresponding orifices in the alignment coupler. The means for releasably locking the ferrule in the housing of the alignment coupler typically includes a plug body housing the ferrule, the plug body including a pair of outwardly extending ridges; and a coupler body with a channel for receiving the coupler housing and the plug body, the channel of the coupler body including a pair of latching members biased over the outwardly extending ridges of the plug body, the plug body further including a sliding mechanism for urging the latching members away from the outwardly extending ridges to remove the plug body from the coupler body.
In the preferred embodiment, the means for sealing include a coupler body with a channel for receiving a connector plug and the alignment coupler therein; and a door spanning the channel, the door biased to cover the channel but displaceable with respect to the channel when the plug body is received in the channel to prevent light from escaping the channel when the plug body is removed from the channel. Usually the door is hinged on each end to the channel and includes at least one spring biasing the door in a position spanning the channel.